I live in an old building with a set of 3 solid wood exterior doors, which my landlord has left to rot and has not varnished in years. The varnish has completely disintegrated in the lower parts which are more badly hit by sun and water. You can literally rub it away by hand.

I've decided to varnish at least the bottom parts, so as to protect them from another harsh winter--otherwise, I don't think they will survive. Not interested in perfect looks, just to protect the wood and a reasonable match.

Problem is, where the wood has been damaged, anything you apply greatly darkens the wood--so it becomes really different from the upper parts which have some of the old finish there and take the varnish without darkening.

Sanded down to the bare wood, it looks like a gray wood. Once you apply any finish, it turns a very dark cherry.

To add to the complication the old finish which has survived nicely in the upper parts seems to be some amber colored varnish. It is NOT a stain, but a rich, golden amber finish that sits on the surface of the wood. It almost looks like shellac, but it could not possibly be, I suppose, as it would not last outside.

I have tried using a wood conditioner, a gel stain, water based exterior urethane and spar urethane (separately of course, on different spots)--all produce a darkening in the bottom, bare parts.

It seems to me now that the old finish simply had a pigment that produces a color sitting on top of the wood, and covering the bare wood color. But what could that be? I have not found anything on the market that would work for outside.

Yes, of course the color has changed with the sun and weather, I'm not expecting a perfect match, but I still want to know what varnish looks like it has some dye in it. This is not simply multiple layers of varnish.

The existing old finish may well be shellac. Lots of it has been used over the decades for exterior projects because lots of folks don't know any better. To determine if it's shellac, wet an area on the upper portion of the door with some denatured alcohol and keep it wet for a minute or so. Then try rubbing the finish off with a clothor a piece of #000 or #0000 steel wool. If it comes off, it's almost certainly shellac. You can then strip the rest of the door this way also.

If it doesn't come off with the alcohol, thenit's most likely an oil-based varnish. All oil-based finishes amber with the passage of time.

Most woods will turn gray in color when unfinished and exposed to these types of weather extremes. Sand deep enough and you'll likely find wood cells that aren't as fried. However, if this door has been left without finish for a long time...you would likely have to sand quite deeply and that isn't really practical.

From what you describe, I would likely resign myself to coloring the entire door the same dark color (or darker) than the lower portions turn when finish is applied. This will entail stripping the entire door first, of course. If you don't the wood won't be able to absorb the stain.

Once stained, apply a couple/few coats of a quality exterior spar or marine grade varnish.

Note the specific instructions for adding these dyes to oil-based finishes.

Frankly, I would not put the effort or money into applying a colored varnish over doors that are bearing old finish and really need more attention. In doing so you would make stripping them in the future all that more difficult and expensive.

If you don't think these doors are worth the effort of doing the job right because they aren't going to survive for long anyway...I would suggest sanding them enough to remove any flaking finish and then paint them. Quicker, faster and cheaper. (Prime the bare wood areas first before painting, of course)

Thank you for the really helpful response (and the great site for the tints!). This was really informative and thorough!

I did do the test before I started, but I did not use denatured, but 91% alcohol. The varnish did not get affected at all, from which I concluded it was probably oil-based varnish.

In retrospect, maybe the alcohol I used was not strong enough--I think I will give it one more try with the real thing.

But one more question:

Someone told me you could use shellac as a base and then cover it with some spar urethane, for exterior protection--that they had done it. The Minwax people said that the wax in the shellac will not allow the urethane to adhere. And that is what Zinsser says too.

Has anyone tried this? Again, I am not looking for a long-lasting, perfect job, but for a finish that will last until the landlord decides to strip the whole thing and do it from scratch.

They are absolutely beautiful, solid doors, it would be a shame to paint over them--or, worse, to let them get destroyed...

Yep...
Paralleling the above poster's opinions, the ONLY way to get a reliable finish is to sand/strip old finish off; AND to sand until the wood looks EVEN again.

And yes...forget Shellac for outdoors.

DON'T leave more color here vs. there. It won't take new stain evenly. Step up through the grits when sanding.
* Use same sanding papers/techniques across ENTIRE door.
* Apply stain.
* Remove ALL dusts.
* Now 3-5 coats of a SPAR Polyurethane, lightly sanding between each coat.
* Sorry...2 coats only STARTS to look even.
* With good tools/techniques, it shouldn't take too long.
* The main ingredient is elbow-grease...and some time!!

One thing that should be pointed out though, you need your landlords permission to be doing this. Otherwise if it turns out badly, and that would be by his standard, you could be stuck with replacing the doors or having to pay to have them redone.
Jack

Thanks to all for all the helpful comments, that have clarified things.

As for Jack's wise warning, I had to take advantage of the good weather and I've taken my risks. The building is managed by a manager for the owning company; he's a cranky guy, whose budget has been so strained over the last few years, he's not even cleaning the common parts on a regular basis, nor fixing leaks.

I've been telling him for 3 years the doors need fixing and he has done nothing.

I could just not bear another winter of seeing the wood suck up all the water from the rain and stay wet for days and slowly rot, as it has in some parts.

As for things turning out 'bad', yes, the darkening means the color is uneven, but (a) the doors already have different color finishes on the front and back (even the sides! they have a dark mahogany color), they're a mess and (b)the wood is at least solidly protected with 3 coats of spar urethane, which means it will at least last through the winter and until he decides to do a proper job.

They don't look perfect, but they look protected and well kept. I'm happy.

This used to be a beautiful building, they don't make doors like these often...

People say he should actually pay me! I'm not holding my breath. Let's not hope he thinks i have to pay him...

You state that the greyed wood turns a dark cherry red when a finish is applied. You could well have a mahogany door and that is the natural color of the wood rather than a stain. Ultimately, stripping the whole door will give the best results. A lot of work on someone else's house!

Yes, shellac can be used under a urethane or polyurethane....although the poly is not exterior rated and should not be used for this. Stick with a spar product of some manner. If you use an oil-based product, several/numerous coats are possible. Waterbornes on the other hand cannot be built up in the same manner or problems can/will develop. Read the directions on the can of WB as it should tell you how many coats are permissible.....and how much time to allow between coats. (This will vary depending upon temps and relative humdity levels. Don't rush it or you'll end up with undried/cured layers underneath. Also........don't use a WB if temps are below 60-ish or humidity is high) If in doubt....call the manufacturer's tech line.

And yes.......the contained waxes in common shellac *can* interfere with the adhesion of polys or urethanes. Play it safe and use a dewaxed shellac product such as Zinnser's Sealcoat. (available at nearly all paint stores and big-boxes).

However, in this instance........there may be no need or sense in using any shellac at all. I'm thinking just apply the urethane directly over what's there....... after prepping that appropriately, of course. (clean and scuff sand....if you're not going to completely strip the doors.)

These are all tough calls to make from here without being able to see the doors firsthand.

Another potential option for you to consider is Sherwin-Williams Duration deep color base.............gloss sheen.......with no pigments added. It looks white in the can, but will dry clear...just like Elmer's glue. Yes, they will look at you as though you are nuts when you want to buy it that way and will tell you it won't work. I had the same problem here. Then I showed them differently with some tests/demonstrations. It's three years later now and those samples have been hanging out back of their store year round taking in the sun, rain and snow. The manager told me about a month ago that she was convinced and so used the stuff on her own front doors. Highly flexible film that adheres great and performs admirably. Or at least has for me in this locale.

I have been researching the same problem and wanted to try an oil based paint base and I cannot find it. I tried Benjamin Moore oil deep base. It looks green and dries to a green cast. More immportantly it takes a day and a half to dry. Perhaps there is a drying agent in the tints. Nearly everyone has stopped carrying oil based and gone to latex.
I looked up Sherwin Williams Duration and it is latex. Is the test Goldhiller refers to a latex or oil deep base?

Goldhiller is right. Denatured alchhol will dislve shellac fast and you do NOT want to re-use it for the exterior. If it is shellac, clean it all off and snd it to get to clean wood. A Spar marine varnish or eurathane will do better than alot of other products for the outside but clear finishes don't hold up long if exposed to direct sunlight. Sure is pretty though!